Casting robot comprising a weighing cell

ABSTRACT

A casting robot ( 1 ) which includes a pivoting device for a foundry ladle ( 3 ) that is suspended by the casting robot is provided. At least one weighing cell ( 23 ) is located in the area connecting the foundry ladle ( 3 ) to the casting robot ( 1 ). The cell is used to dynamically measure an instantaneous amount of molten material present in the foundry ladle ( 3 ) or the amount of molten material poured into a casting mold ( 7 ).

BACKGROUND

The invention is directed to a casting robot according to the preamble of claim 1.

When large numbers are to be produced today the production of mold castings occurs primarily with partially automated or fully automated casting robots. In order to allow an amount of liquid melt, determined as precisely as possible, to flow into the mold, various weighing devices are known, by which during the casting the amount of matter removed is determined via the different weight of the foundry ladle prior to and after the casting. Depending on the type of suspension of the pivotal foundry ladle, measurement cells for determining the present weight are to be arranged below the casting machine and, in this way, they measure not only the melt and the foundry ladle but also the other elements of the casting robot. Such devices are disadvantageous in that the weight of the amount of melt to be measured, flowing into the mold, is very small in comparison to the total weight of the machine and therefore respectively great measurement errors can occur.

In DE 4028918 A1 a weighing cell is suggested, which is used between the foundry ladle and the pivoting device at the pivoting robot. This weighing device serves to perform a measurement of the weight difference between the empty foundry ladle and the one filled with melt, in order to determine the casting process using this parameter. Any details regarding the technical embodiment of the measuring device, except for the location of said measuring, is not disclosed in this technology of prior art.

SUMMARY

The objective of the present invention is to provide a casting robot with a weight measuring device, by which the liquid melt dispensed, flowing into the mold, can be measured exactly.

This objective is attained by a casting robot having the features of claim 1. Additional advantageous embodiments of the invention are defined in the dependent claims.

By the arrangement according to the invention of at least one weighing cell and at least one motion sensor connected to said weighing cell it is achieved that the liquid melt introduced into the mold can be measured within narrow tolerances and thus exactly the required amount of melt can be introduced into the mold.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

Using the illustrated exemplary embodiments, the invention is explained in greater detail. In the drawings:

FIG. 1 is a side view of a casting robot having a foundry ladle arranged in a horizontal position, i.e. in the original position,

FIG. 2 is a top view of the casting robot,

FIG. 3 is a perspective top view onto the support plate from the direction of arrow 5 (foundry ladle not suspended)

FIG. 4 is one possible embodiment of a weighing cell from the front,

FIG. 5 is a view of the weighing cell in FIG. 4 from the direction P,

FIG. 6 is an enlarged representation of the carrier plate (view from the top), and

FIG. 7 is an enlarged representation of the carrier plate (side view).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, a casting machine is shown, referred to as casting robot 1 in short, partially hidden by a suspended foundry ladle 3. The casting robot 1 can be displaced on first rails 5 in the Y-direction, i.e. along a number of molds 7. It can further be displaced on second rails 9 in the X-direction, i.e. in the direction towards the molds 7 and away from them. The foundry ladle 3 can be displaced vertically, i.e. in the Z-direction along a tower 11 at the casting robot 1, and additionally it is pivotal on a defined path positioned in the Y-Z level. The pivotal motion of the foundry ladle 3 can, for example, occur according to the features of WO 99/00205. Here, the lip 13 of the foundry ladle 3 is guided over the inlet funnel 15 at the mold 7 such that the liquid metal melt exiting the foundry ladle 3, can essentially flow coaxially into the inlet opening at all times. The process for pivoting the foundry ladle 5 is not included in the invention; it is merely a potentially advantageous way for an optimum production of mold casting.

The foundry ladle 3 is laterally connected in a detachable manner to a receiving plate 19 at the tower 11 by way of a catch part 17. Between the receiving plate 19 and a holding plate 21 at the tower 11, similarly shaped as the receiving plate 19, at least one weighing cell 23 of a known design is used. The measurement of the weight of the foundry ladle 3 and the melt can occur, for example, by way of a plunger coil or a wire strung between the load side 23′ and the fastening side 23″ of the measurement cell 23, its oscillation value changing dependent on the load. Such measurement cells 23 are also used in scales and are known from prior art. Certainly, other measurement means, such as measuring cans can be used as well, to the extent they can provide sufficient resolution.

A measurement cell 23 having a wire strung between the load side 23′ and the fastening side 23″ (wire not shown) is illustrated schematically in the FIGS. 4 and 5. The measurement cell 23 is connected by suitable fastening means, for example screws, on the load bearing side to the receiving plate 19 and on the fastening side to the holding plate 21. In the normal position, i.e. when the upper surface of the foundry ladle 3 is horizontal, the load axis A, i.e. the axis in which the load is optimally introduced onto the measurement element (wire), is arranged tilted from the vertical V (FIG. 1). The angle of the slope between the axes A and V amounts to X°, i.e. 18°. At a full pivotal extent of the foundry ladle 3 shortly before the complete outflow of the melt, the load axis A of the measuring cell 23 is at an angle Y° of approx. 35° towards the vertical V. This arrangement of the measurement cell 23 allows the achievement of an optimal precision to the measurement, regardless if the direction of the load extends optimally in the load axis A or if the load extends at an acute angle thereto and the result having to be compensated accordingly.

Another increase in the precision of measurement can be achieved when, for example, three measurement cells, as shown in FIGS. 3, 6, and 7, are arranged around an imaginary or actual axle between the receiving plate 19 and the holding plate 21.

Automatic casting devices with casting robots 1 achieve high efficiency only when the individual movement processes, such as the pivoting of the foundry ladle or the displacement of the casting robot 1 from the foundry ladle 7 to the foundry ladle 7 and/or from the entry funnel 15 to the entry funnel 15 occurs as quickly as possible. This leads to additional forces (massive forces), which act onto the measurement cell 23 and can influence the result of the measurement. According to the invention, suitable sensors determine these additional forces acting upon the measurement cells 23, and consider them in the measurement result. 

1. A casting robot (1) comprising a foundry ladle (3) suspended on a pivoting device and having a weighing cell (23) between the pivoting device and the foundry ladle (3) for weighing a metal melt contained in the foundry ladle (3), at least one weighing cell (23) is arranged, between a receiving plate (19), from which the foundry ladle (3) is suspended, and a holding plate (21), mounted to the pivoting device.
 2. A casting robot according to claim 1, wherein a load axis (A) of the at least one weighing cell (23) in a normal position with the foundry ladle (3) is horizontal, and is positioned tilted by an initial angle (X°) in reference to a vertical (V), and at a maximum travel of the foundry ladle (3), the axis (A) is tilted to the other side by an angle (Y°) after having passed through the vertical (V).
 3. A casting robot according to claim 2, wherein the initial angle (X°) is smaller than the angle (Y°).
 4. A casting robot according to claim 3, wherein the initial angle (X°) is approximately 18° and the angle (Y°) prior to complete emptying is approximately 35°.
 5. A casting robot according to claim 1, wherein the at least one weighing cell comprises three weighing cells (23) are distributed around an actual or imaginary pivoting axis (B) and are arranged between the receiving plate (19) and the holding plate (21).
 6. A casting robot according to claim 5, wherein the axes (A) of all weighing cells (23) are positioned parallel to one another.
 7. A casting robot according to claim 5, wherein the axes (A) of the weighing cells (23) are positioned at an angle to one another in each pivotal position of the foundry ladle (3).
 8. A casting robot according to claim 1, wherein weighing sensors are arranged for detecting weight changes of the foundry ladle (3). 